Laser-induced cavitation bubble near boundaries

Journal of Hydrodynamics, Год журнала: 2023, Номер 35(5), С. 858 - 875

Опубликована: Окт. 1, 2023

Язык: Английский

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A novel method for predicting fluid–structure interaction with large deformation based on masked deep neural network

Physics of Fluids, Год журнала: 2024, Номер 36(2)

Опубликована: Фев. 1, 2024

Traditional fluid–structure interaction (FSI) simulation is computationally demanding, especially for bi-directional FSI problems. To address this, a masked deep neural network (MDNN) developed to quickly and accurately predict the unsteady flow field. By integrating MDNN with structural dynamic solver, an system proposed perform of flexible vertical plate oscillation in fluid large deformation. The results show that both field prediction structure response are consistent traditional system. Furthermore, method highly effective mitigating error accumulation during temporal predictions, making it applicable various deformation Notably, model reduces computational time millisecond scale each step regarding part, resulting increase nearly two orders magnitude speed, which greatly enhances speed

Язык: Английский

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Theoretical and experimental investigation of a bubble collapsing near an asymmetric hydrofoil

Physics of Fluids, Год журнала: 2024, Номер 36(2)

Опубликована: Фев. 1, 2024

In the present paper, restricted cavitation bubble dynamics near an asymmetric Joukowsky hydrofoil are investigated theoretically and experimentally. This investigation employs conformal transformation, image method, Kelvin impulse model, together with high-speed photographic experiments. The characteristics of collapse deformation wall movement analyzed qualitatively quantitatively, spatial distributions liquid velocity revealed by theoretical predictions. main conclusions include (1) deformations can be divided into three typical cases: penetrating (mostly occurs when γ<2 γ defined as bubble-hydrofoil dimensionless distance), triangular depression 2<γ<4), arc-shaped γ>4). (2) acting on is governed a point source sink, which dominant, inversely correlated distance, corresponds to experimental results. (3) exhibits different at tail, head, middle regions hydrofoil, angle remains basically unchanged in concave region hydrofoils (i.e., range 240°<θz<350° θz position angle).

Язык: Английский

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Improved prediction of turbomachinery flows using Reynolds stress model with γ transition model

Aerospace Science and Technology, Год журнала: 2023, Номер 144, С. 108812 - 108812

Опубликована: Дек. 6, 2023

Язык: Английский

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Hybrid RANS-LES Simulation of Rotor-Stator Interaction in a Compressor Stage Using Grid-Adaptive Simulation Method

Journal of Turbomachinery, Год журнала: 2024, Номер 147(7)

Опубликована: Ноя. 7, 2024

Abstract Flows in compressors are extremely complex with various scales. Small-scale turbulence, middle-scale rotor–stator interaction (RSI), large-scale corner separation, and tip leakage flow should all be considered the simulation of compressors. Recently, a new hybrid Reynolds-averaged Navier–Stokes-large eddy (RANS-LES) strategy that modifies turbulent viscosity equation based on Kolmogorov energy spectrum, termed grid-adaptive (GAS) method, is proposed by our group to achieve high accuracy using different grid resolutions. In this study, GAS method shear stress transport (SST) turbulence model employed simulate RSI just RANS-like resolution single-stage transonic compressor TUDa-GLR open test case. Compared experiments other methods (including RANS delayed detached (DDES) methods), results show can significantly improve prediction for stall margin radial distribution parameters. Then, effect secondary structures analyzed unsteady field simulated method. Results incorrect rotor vortex breakdown underestimation mixing losses region blamed deviation RANS. An intuitive total pressure fluctuation caused wakes observed stator inlet. The particle tracking shows wake from suction surface has strong trend into stator. Spectral proper orthogonal decomposition (SPOD) also utilized. Unsteady temporal–spatial induced local unsteadiness distinguished SPOD, which includes reverse wave generated RSI. SPOD found separation side exhibits an frequency 1.6 blade passing (BPF).

Язык: Английский

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Unsteady Flow Mechanism of Corner Separation Control Using Blade End Slots in a Highly Loaded Compressor Cascade

Journal of Turbomachinery, Год журнала: 2024, Номер 147(6)

Опубликована: Ноя. 27, 2024

Abstract Blade end slots have been proven to be an effective method suppress corner separation, thereby improving the aerodynamic performance of compressor. The unsteady effects blade affiliated with a highly loaded compressor cascade on separation control are investigated based delayed detached eddy simulation under Mach number 0.59. vortex structures between datum and slotted compared. topologies markedly reorganized suppressed by slots. Unsteady flow behaviors corresponding dynamic mechanisms analyzed in both time frequency domains. interaction self-adaptive jet from results smaller-scale vortices region higher characteristic frequency. Consequently, caused significantly reduced range intensity through enhancement mixing rapid dissipation into larger-scale lower-frequency features. Furthermore, spatiotemporal features dynamics slot using enhanced mode decomposition method. Results show that dominant behavior develops better stability, intermittency low-frequency large-scale is via control.

Язык: Английский

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Mechanisms of mass transfer effect for the vapor-gas bubble under acoustic excitation

Physics of Fluids, Год журнала: 2025, Номер 37(1)

Опубликована: Янв. 1, 2025

This paper theoretically explores the mechanisms of mass transfer effect for vapor-gas bubble under acoustic excitation. The mathematical model mixture is established based on perturbation method. threshold different vapor fractions compared with those gas bubble. represents amplitude condition at which molar quantity within achieves dynamic equilibrium state, dictates whether expands or contracts. main conclusions are summarized as follows: (1) fraction inside has a significant processes, including growth, diffusion, and convection. (2) As initial valor increases, resonance region moves in direction decreasing radius. In far above resonance, curves show either an upward trend downward trend. (3) radius, fraction, value all undergo variations during bubble's growth shrinkage processes.

Язык: Английский

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Hydrodynamic analysis of hydrofoil cavitation based on adaptive mesh theory

Physics of Fluids, Год журнала: 2025, Номер 37(3)

Опубликована: Март 1, 2025

Cavitation is a transient multiphase flow phenomenon involving complex turbulence, liquid–gas phase transitions, and pressure fluctuations, which can cause cavitation erosion, vibration, noise in hydraulic machinery. This study employs volume of fluid–adaptive mesh refinement (VOF-AMR) coupled model to conduct large eddy simulation (LES) cavitating around National Advisory Committee for Aeronautics 66-series(NACA66) hydrofoil, focusing on cavity shape transitions the dynamics discrete cavities reentrant jets. Results show that LES-VOF-AMR improves accuracy, with shedding frequency prediction error within 0.3%. The transition from two-dimensional sheet-like three-dimensional cloud-like characterized by an increase vapor growth rate. During collapse, jet dominates near-wall suction side, shifting high-frequency fluctuations lower frequencies, indicating coupling effect between hydrofoil vibrations pulsations. vortex exclusion effect, caused jet, primary driver rapid collapse. Cavitation–vortex analysis highlights impact wall shear wake dilatation terms, while stretching baroclinic torque influence vorticity intensity. These findings advance understanding cavitation–vortex provide theoretical support control

Язык: Английский

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Gray area mitigation in grid-adaptive simulation for wall-bounded turbulent flows

International Journal of Mechanical Sciences, Год журнала: 2025, Номер unknown, С. 110305 - 110305

Опубликована: Апрель 1, 2025

Язык: Английский

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Effect of moving end wall on tip leakage flow in a compressor cascade with different clearance heights

AIP Advances, Год журнала: 2024, Номер 14(1)

Опубликована: Янв. 1, 2024

Numerical simulations have been carried out to investigate the effect of moving end wall on tip leakage flow structure in a compressor cascade with four different clearance heights. A detailed comparison flow’s loss; mass rate; and vortex its roll-up, trajectory, size, interaction passage was made. The results show that performance changes more severely as height increases than stationary wall. roll-up has studied by analyzing pathline vorticity distribution. An alternative explanation is proposed for initial mechanism vortex. transport responsible vortex, whereas jet/passage shearing development. smaller is, easier it alter from gap

Язык: Английский

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